Wireless LANs have pervaded our everyday lives and are now almost ubiquitous in our work-places and our homes, providing greater connectivity and enhancing the quality of our ever information-dependent lifestyles. With new developments in communications technology, physical transmission speeds over wireless networks are now substantial enough to support AV transmission. However, due to the inherent nature of AV traffic streams, the network must be able to provide a certain level of QoS to meet end-user satisfaction. This invention pertains to a system that can handle and schedule both time sensitive traffic (such as AV) and non-time sensitive (such as traditional file transfer applications) traffic over the same wireless network.
“Local and Metropolitan Area Networks-Specific Requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications”, IEEE Std 802.11-1999, IEEE, August 1999 discusses a cost-effective solution for networking computers and other devices, wirelessly. With enhancements to signal processing and modulation technology, the enhancements to the standard were made so as to support higher data rates using new physical layers, see e.g., “Local and Metropolitan Area Networks-Specific Requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-Speed Physical Layer Extension in the 2.4 GHz Band”, IEEE Std 802.11b-1999, IEEE, September 1999 and “Local and Metropolitan Area Networks-Specific Requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-Speed Physical Layer Extension in the 5 GHz Band”, IEEE Std 802.11a-1999, IEEE, September 1999.
The latest version of the standard that is being developed is in the form of enhancements to the MAC layer for supporting QoS—an essential requirement for AV devices, see e.g., “Draft Supplement to LAN/MAN Specific Requirements—Part 11: Wireless Medium Access Control (MAC) and Physical Layer (PHY) specifications: MAC Enhancements for Quality of Service (QoS)”, IEEE Std 802.11e/D4.0, November 2002. While the standard defines protocols and mechanisms for supporting AV traffic, it does not describe a system for achieving the same.
While IEEE 802.11e specifies MAC level protocols and mechanisms for improving the throughput and providing for QoS in a wireless network, it does not provide for a system that can achieve the same. With wireless LANs gaining increasing popularity and ubiquity, newer applications such as AV and multi-media transmissions over them are being developed. This invention addresses the problem of scheduling and admission control in the wireless network, a role that is delegated to a centralized medium coordinator in the network. The standard specifies an attribute that constrains the maximum amount of bandwidth that may be used for QoS traffic during each super-frame of the wireless network. This invention addresses the problem of determining traffic stream admission depending on resource availability and stated requirements. It also solves the problem of generating an optimized schedule so as to most effectively fully utilize the wireless bandwidth.
With improvements in device technology, electronic equipment is steadily shrinking in size, while rapidly expanding in functionality. While handheld wireless computational devices have already made their debut, there is an ever-increasing need to minimize power consumption, thereby improving battery life and providing for smaller and lighter weight terminals. This invention also describes a mechanism for the centralized coordinating node of the wireless network to introduce power-saving features on the stations, thereby improving their performance.